This invention concerns dishwashers and more particularly closure arrangements for dishwasher vent openings. Such openings are provided to enable escape of the relatively hot humid air within the interior of the dishwasher cabinet during the drying cycle such that drying may be facilitated. Since the escape of humid air and dishwasher noise during the wash and rinse cycles should be avoided, dishwashers incorporating such vent openings typically have incorporated some arrangement for closure of the vent openings during the wash and rinse cycles.
The conventional approach is to provide a flapper valve mechanically operated by means of a timer-controlled solenoid or a similar control arrangement. Such components are subject to wear and failure and thus increase the manufacturing cost and maintenance requirements of such dishwashers.
In U.S. Pat. No. 2,909,184, there is described a vent closure arrangement in which does not require such moving parts and controls. In this arrangement, a horizontally disposed retaining pan is provided into which extends a flanged water inlet opening, which opening establishes communication in between the cabinet interior space and the exterior vent opening. This retaining pan is positioned with respect to the end of the flange such that when the retaining pan is filled with water, a water seal of the vent is created. Water is maintained in the retaining pan during filling, wash and rinse cycles, but is allowed to drain away during the drying cycle through a drain hole located in the bottom of the retaining pan. While this achieves the desired objective of eliminating moving parts and the necessary controls, the particular configuration of the vent opening between the flange and the retaining pan substantially retards vent air flow.
The relationship between the vent flow and the configuration of the vent opening may be critical in those designs relying on convection currents to set up the proper air flow within the cabinet and the air flow itself must be carefully controlled in order to achieve an efficient drying process, requiring the minimum amounts of drying heat.
Accordingly, it is an object of the present invention to provide a vent closure arrangement and method for dishwasher vent openings which does not involve the use of moving parts or controls therefor, but in the open condition, the vent opening does not significantly retard the flow of vented air from the dishwasher interior.
It is a further object of the present invention to provide such an arrangement which incorporates relatively simple components which may be manufactured at relatively low cost.